Paper currency number recognition apparatus and recognition method

Abstract

A paper currency number recognition apparatus and method. The apparatus comprises: a contact-type sensor ( 10 ) for acquiring paper currency image data; a white-light LED transmission light source board ( 20 ); an image acquisition processing board ( 40 ) which is integrated with an FPGA and a DSP, the FPGA being used for controlling ON/OFF of the white-light LED transmission light source board ( 20 ) and driving the contact-type sensor ( 10 ) to acquire an image, and the DSP being used for processing and recognizing the paper currency image data; and two pairs of position sensors ( 30 ) for detecting whether there is a paper currency entering the paper currency number recognition apparatus, wherein the white-light LED transmission light source board ( 20 ) has two light source modes which are strong and weak, and the two light source modes alternately provide a transmission light source for the contact-type sensor ( 10 ) to acquire the paper currency image data. The apparatus can acquire two white-light transmission images with different brightness of one and the same paper currency each time; therefore, the numbers of both new and old paper currencies can be effectively recognized, and the accuracy rate of paper currency number recognition is improved.

What is claimed is: 
     
       1. A paper currency number recognition device, comprising:
 a contact sensor configured to acquire paper currency image data by way of transmission imaging; 
 a white light LED transmission light source board arranged right in front of the contact sensor to provide the contact sensor with a transmission light source for use in collecting the paper currency image data; 
 an image collection processing plate connected to the contact sensor through a data cable, wherein a Field Programmable Gate Array and a digital signal processor are integrated on the image collection processing plate, the Field Programmable Gate Array is configured to control the white light LED transmission light source board to be on or off and drive a CIS to acquire images, and the digital signal processor is configured to process and recognize the paper currency image data; and 
 two pairs of position sensors arranged on a paper currency transport pathway at a position with a predetermined distance from the contact sensor and configured to detect whether there is a paper currency entering the paper currency number recognition device; 
 wherein the white light LED transmission light source board has a strong light mode and a weak light mode, and the two light modes alternately provides the contact sensor with the transmission light source for use in collecting the paper currency image data, and 
 wherein, after the Field Programmable Gate Array completes collection of a row of image data, the Field Programmable Gate Array informs the digital signal processor in a manner of an interruption of acquiring data, and the digital signal processor enters an interrupt service routine and detects an image type register to determine a type of the row of image data. 
 
     
     
       2. The paper currency number recognition device according to  claim 1 , wherein the two light modes are formed by controlling turn-on time of the white light LED transmission light source board by the Field Programmable Gate Array, the strong light mode is formed in a case that the turn-on time is longer, the weak light mode is formed in a case that the turn-on time is shorter, and the ratio between the turn-on time for forming the strong light mode and the turn-on time for forming the weak light mode is 3:1. 
     
     
       3. The paper currency number recognition device according to  claim 1 , wherein a memory is integrated on the image collection processing plate, the memory comprises two buffers and the register, the buffers are configured to store the paper currency image data collected by the contact sensor, and the register is configured to indicate a type of the paper currency image data in the buffers, with 1 indicating strong light image data and 0 indicating weak light image data. 
     
     
       4. The paper currency number recognition device according to  claim 1 , wherein a clock MCLK with a cycle of 0.125 ms and a row counter are provided inside the Field Programmable Gate Array. 
     
     
       5. A paper currency number recognition method, comprising:
 step 1 comprising acquiring strong light image data and weak light image data of a paper currency by way of transmission imaging in the case that a transmission light source irradiates alternately in a strong light mode and in a weak light mode; 
 step 2 comprising performing an edge detection on the weak light image data to acquire four edges of an image to determine a target image; 
 step 3 comprising processing the target image to recognize a version, a nominal value, an orientation of the paper currency and determine an area where the paper currency number is located; 
 step 4 comprising calling a pattern recognition algorithm, comparing a gray value of the paper currency image with a threshold value by using a pattern recognition method based on artificial neural networks to recognize that the paper currency is new or old, and using the strong light image data for recognition in the case of an old paper currency, or selecting the weak light image data for recognition in the case of a new paper currency; and 
 step 5 comprising outputting a recognition result of the paper currency number, 
 wherein, after the Field Programmable Gate Array completes collection of a row of image data, the Field Programmable Gate Array informs the digital signal processor in a manner of an interruption of acquiring data, and the digital signal processor enters an interrupt service routine and detects an image type register to determine a type of the row of image data. 
 
     
     
       6. The paper currency number recognition method according to  claim 5 , wherein four vertex coordinates of the paper currency image are acquired, slope-a slopes of lines at which borders of the paper currency is located is computed by using a least square line fitting method, and four edges of the image are acquired, in step 2. 
     
     
       7. The paper currency number recognition method according to  claim 5 , wherein acquiring strong light image data and weak light image data of a paper currency in step 1 comprises:
 step  101  comprising detecting a state of a position sensor; 
 step  102  comprising judging whether the position sensor is triggered, proceeding to step  103  in the case that the position sensor is triggered, or returning to step  101  in the case that the position sensor is not triggered; 
 step  103  comprising starting to scan to acquire the paper currency image data, resetting a row counter, and proceeding to step  104 ; 
 step  104  comprising detecting a rising edge of a MCLK; 
 step  105  comprising judging whether the rising edge of the MCLK is detected, proceeding to step  106  in the case that the rising edge of MCLK is detected, or returning to step  104  in the case that the rising edge of MCLK is not detected; 
 step  106  comprising switching a LED for strong light irradiation; 
 step  107  comprising driving, by a FPGA, a CIS to collect a row of image data, and proceeding simultaneously to step  108  and step  120 , wherein step  108  and subsequent steps of step  108  are performed in parallel with step  120  and subsequent steps of step  120 ; 
 step  108  comprising detecting the rising edge of the MCLK again; 
 step  109  comprising judging whether the rising edge of the MCLK is detected, proceeding to step  110  in the case that the rising edge of the MCLK is detected, or returning to step  108  in the case that the rising edge of the MCLK is not detected; 
 step  110  comprising switching the LED for weak light irradiation; 
 step  111  comprising driving, by the FPGA, the CIS to collect a row of image data again, and proceeding simultaneously to step  112  and step  120 , wherein step  112  and subsequent steps of step  112  are performed in parallel with step  120  and subsequent steps of step  112 ; 
 step  112  comprising adding 2 to the row counter in the FPGA; 
 step  113  comprising judging whether the count of the row counter in FPGA is equal to 960, proceeding to step  114  in the case that the count of the row counter in FPGA is equal to 960, or returning to step  104  in the case that the count of the row counter in FPGA is not equal to 960; 
 step  114  comprising completing image collection and ending scan; 
 step  120  comprising a DSP entering an interrupt service routine; 
 step  121  comprising detecting the image type register; 
 step  122  comprising judging whether the image data is strong light image data, proceeding to step  123  in the case that the image data is strong light image data, or proceeding to step  124  in the case that the image data is not strong light image data; 
 step  123  comprising storing a row of data into a strong light image buffer; and 
 step  124  comprising storing a row of data into a weak light image buffer.